Most of my amps are based on L shape 4.5mm aluminioum corner that then is attached to the heatsink with bolts and screws ......

In between always and of course is as much paste is possible to ensure better heat transfer from one element to the other.

(Many times crossed my mind to make my own paste made out of the normal white paste we buy at the hardware shops but mixed with aluminioum powder which i can have plenty from local aluminioum shops . Never tryied that but sounds like a good idea )

One other thing i know very well is that not all L shape aluminioum is good to be a heatsink since it is very importand what material is actually made of .

And finally specially made L shape are sold in shops with the iner corner rounded which quicker transfers heat to the main heatsink.

The idea crossed my mind lately is to weld the L to the main heatsink ......since i can do that now i will give it a try and let you know .

In between idlike to listen to your opinion about that

one will say why not buy ready made heatsink that is already shaped to meet your standards ....Then i have to answer that i have so much hetasink in my shop from various projects that i have to convert to fit any amp i construct, and also there is so much heatsink from classic 2N3055 style transistors and i really like to make this usefull again by welding parts on it so it can be used for other devices also

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all is fine here ..... i actually visited this shop in person i think it should be located in a place called solna but may be i am wrong .....( i visited in 1994)

A think i didnt like about the shop is that works with catalogs and a piece of paper that you write down numbers from the catalog and then somebody will bring it out from the stock .....

Shoping parts in greece is a totaly diferent game .....In the shops you go the "tellers" are edjucated and highly expirienced people in electronics and they know replacements by hurt ( often they dont need to open a book ) then you can also talk about the quality or specs of the product and of course and more importand there you will meet others that share simular needs ,problems, and so on .....so you can talk about your project there ......

May be takes more time but hell !!! shoping is much more fun like that

most times i look at your posts there is always a usefull comment or information .....

this is ok if you need to construct one amp then you had the chance to design like this which is not a bad idea ( but actually eventhough seen it before i have second thoughts on what happens to the pcb if the transistors warm up more than they suppose to ****read my signature *****)

in my case i have right infront of me .....today about 15 amps either to be repaired reconstructed ....others constructed from scratch ....some of them are mine and they are to be repaired and then back to work in small PA rentals that i deal with and then some more amplifiers that are constructed for costumers on special demands and requests .... and a couple of projects that are other peoples ideas which i mod to my taste ....

so with all this volume of work and also all this stock of various heat sink the ability of flexible is a must .....

i ll post pictures any day now about this ....but first i need to make thermo tests

the question remains :

if the L shape will perform beter with paste bolts and screws or welding

The easiest way to show you is to do it on a computer CPU chip... as it has digital temperature tracking on your screen...

The trick is to use a high quality thermal compound... the quality computer brands do very well...in terms of how long it lasts, espicialy when applied as thin as possible as per recommendation...

If you can make a copper mounting plaste I suggest you try Coollaboratory Liquid Pro, it will eat aluminium if it gets in contact with it though... this stiuff has 10 times the thermal transfer rate of traditional thermal compounds...